If the revelations that Trump has fantasized about incest with his own daughter, cheated on all of his wives, had sex with pornstars and paid them off, bribed government officials, has gone bankrupt multiple times, has been sued by fraud multiple times, is enriching himself using public funds, is accepting money from foreign governments and making political decisions based on that, has attempted to coerce a foreign government into acting against a US citizen, has interfered with criminal investigations, has covered up and destroyed evidence of criminal actions, and is possibly suffering early on-set dementia isn't enough bad press...

What do you think are going to be the actual repercussions, in the US, of learning that the US president is trying to secure exclusive US control of a vaccine for COVID19 for priority distribution in the US?

They aren't going to be any. Indeed, to his base, stuff like this is exactly why they voted for him. (If Trump had succeeded in securing that vaccine solely for the US, he would win in November in a landslide.) And that's pretty much the extent of the calculations that went on in his head when he attempted this stunt.

It's a good thing he failed. But let's be responsible about disclosure and time it so that he can't derive any political benefit from it.